The invention discloses a method used for detecting content of ponceau 4R in beverage via CdTe quantum dot fluorescence quenching. According to the method, a CdTe quantum dot probe is taken as a fluorescent probe, high selectivity and high sensitivity detection is carried out based on the characteristic that fluorescence intensity of the CdTe quantum dot probe is reduced along with increasing of the concentration of ponceau 4R; excellent linear relation of the changing value of the fluorescence intensity of the CdTe quantum dot probe with the concentration of ponceau 4R is shown, and the square of correlation coefficient is 0.995. The method is simple in operation, high in sensitivity and selectivity, and rapid in detection, and is suitable for on-site in-situ analysis.